Steam drying system



s'rsm RY NG. 'SYS m. Filed Sept. 28 11920 Lwa STEAM Em usr STEAM F. c.FARNs wbRTH INV E Ni OR ATTORNEY whereby high efficiency is PatentedMar. 31, 1925.

PATIENT, OFFICE,

v UNITED STATES FREDERICK G. FARNSWORTH, OFNORRISTOWN, PENNSYLVANIA.

STEAM DRYING SYSTEM.

Application filed September '28, 1920. Serial No. 413,421.

To all 11710722 it may concern: Be it known that I, FREDERICK C. FARNS-wou'rma citizen of the United States, andreturn water-ct condensation,said condensa-- tion constituting feed water to the boiler equipment. 7

This invention relates to a system of drying employed in paper millmachinery and utilizing live or exhaust steam for heating he dryingcylinders, the said cylinders being arranged in sections known as a dryend section and a wet end section, the steam delivered from the dry'endsection being separated from the water of condensation and delivered tothe wet end section in which it'is usually condensed and the water ofcondensation and any escaping vapors discharged to the sewer. The mainor dis tinctive feature of my improvement in the preferred form residesin circulating of the steam through all of the dryingcylinders at apressure above atmospheric pressure and insuring tree flow of the steamentirely through the system by causing the steam after passing from thewet end drying cyl- .inders tq be condensed in a continuous manner toremove all back pressure, and at the same time utilizing the localvacuum produced thereby to'cause the water of condensation to be rapidlyremoved from the discharge side of the drying cylinders, whereby thewater is collected and removed and the steam is caused to flow freelythrough all of the drying cylinders.

My object, is furthert-o provide a substantially constant predeterminedheating condi tion all times in the paper making ma- (.llIik. wherebythe drying cylinders on the dry end are hottest and the temperaturegradually decreases as the wet end is approached, the circulationthrough all of the drying cylinders being done at pressures aboveatmospheric pressure and said pressure decreasing from the dry end tothe wet end, from which latter the air, water and steam are removed.

More particularly, 'my object is to operate the drying cylinders insections, and where there are two sections, viz: the dry end sectionformed by approximately seventyfive per cent of the dryers, as relatedto twenty-five per cent of the dryers on the wet end section, the lattersection is sup plied with. has passed through the dry end cylindersaccompanied by water of condensation and air, the water'of condensationformed in the dry end section being automatically sepa-' rated from thesteam before it reaches the wet end section and at all times retainedunder pressure to maintain its temperature,

prior to its return to the boiler as feed water; andfurther, the objectis to cause thesteam fromthe dry end sections to pass mto and throughthe wet end cylinders and v the uncondensedsteam, which partly condense,the remaining uncondensed steam being utilized in an automatic duplexcondensation pump or other pumping device for creating and maintaining apartial vacuum, utilized to directly act to suck the water and air fromthe wet end cylinder and returns, removing all back pressure from steamand delivering the hot condensation water to the boiler feeder with aminimum loss of heat units.

As a further object of my invention, I provide a communication betweenthe steam supply to the dry end section and supply to the wet endsection, in which is arranged automatic pressure reducing valve devicesadapted to insure additional steam (preferably from the same source assupplies the dry end section) to the, wet end section when insufficientsteam is passing through the dry end section to meet the dutyrequirements of the wet end section of drying cylinders, such forexample, as when in-. suli'icient initial steam pressure is available orwhen the stock being dried is extra thick and wet and hence requiringmore steam in the dryers without impairing the function of the duplex orother condensing pump as a vacuum producing means for taking care of thewater of condensation and insuring circulation. i

i it

As a a further improvement in my.- improved system, the .dry end sectionofthe drying cylinders is extendedand divided as a final operatingunitfor-specially meeting the heavy duty in drying paper board asdistinguished from the necessities incident to drying of. thin papers inweb form.- My object in this part of my invention is to increase thenumber of drying cylinders and supply them with exhaust or live steam,as may be convienient or necessary, and whereby it is possible to supplylive steam of higher pressures in the divided exten- "sion of the dryingcylinders than those employed in the dry'end section next adjacent tothe Wet end section, with the result that the paper fboard is subjectedto the 'heat of graduallyincreased' steam pressures to insure properdrying, or on the other hand, to supply the extended sections withexhaust steam of the same pressure as supplied to the dry end sectionnext to the wet end section. 'It is "further my object, in embodyingthese: extended-sections of drying cylinders to provide-auto- -maticpressure reducing means 'for said secdensation received from the finalsection may .be forced by the steam pressure to the boiler and deliveredtherein by a duplex-boiler'feeder.

By reason of the carrying out of the above stated objects and results,-I am enabled to provide drying capacity to suit 'all characters of workand duty; and at the same time, heat units available in the water ofcondensation and in the steam condensed -in or in connection with thepumps used for handling'the water and for maintaining the partial vacuumdesired, maybe all returned tothe boiler as 1 elements of the feed waterand whereby the system asa whole is operated-under high inafter set out,my invention consists inthe Withuthe-abov and other objects here-'1method and means for securing the desired results and comprising thefeatures hereinafter described and more particularly defined intheclaims.

Referring to the drawings Fig. 1 is a- ,genera'l side. elevation. of adrying apparatus of a paper, making mill embodying my improvements; andFig. 2 is a sectional elevation of the pressure reducing valve devicesfor automaticallyby passing steam from the supplyof one drying seetionto the supply of the next "drying section in advance.

Considering first, the wet end divisions comprising the wetend section 6and dry end section6 the source of steam'supply may be, the exhauststeam pipe 19 from which steam is admitted to pipe 21 by valve 20 andthereby supplied to the steam header 23 from which it is delivered tothe drying cylinders of section 6 The pressure of this exhaust steam maybe assumed to be fifteen pounds as indicated by" gauge G on pipe 21. The.water of condensation, air and uncondensed steam from the dryingcylinders are delivered into a return header 24 which drains into ahorizontal pipe 27 discharging into a steam separator 26. From theseparator the water of condensation drains by pipe 28 and enters thecondensation pump 29 (to be later de scribed) and by which the water isdeliv- -ered,,. under pressure, by pipe 30 to the mains 15 and 42 to theduplex boiler feeder 43 (to be later described) and from which.

.itis delivered by pipe 44 into the boiler 15.

The steam leaving the separator 26 passes by elbows 31 into the supplyheader 32 for the cylinders of the Wet end section- 6; and the steam maybe assumed as of ten pounds pressure, as indicated on one ofthe gauges Gceived from the returns of the dry end section 6, issupplied under itsinitial pressure through the drying cylinders of the wet end section 6and the water of condensation and air released therein are dischargedinto the returnheader 33 at a reduced pressure which may be assumed asseven pounds, as indicated on the gauge G connected with said returnheader. The water and air blown from the-wet end cylinders into thereturn header, pass by pipe This steam, thus re- I 38 to the.suctioninlet of the duplex cont ensation pumpv39 (to be later described) havingthe cold water spray jets 10 by -Whi ch it condenses the steam andcreates and maintains a partial vacuum, the condensation of the steamand thereby removal of the back pressure, permitting the free flow ofthe steam through the dryers at a pressure above atmospheric pressure.The water-of condensation blown from the dryer cylin ders and receivedby this pump 39, is forced .under pressure through pipes 41 and-t2 intothe duplex boiler feeder 43 and delivered to the boiler 4F.v forspraycondensationvis supplied by a pipe 4Q. It will be specially notedthat the steam is circulated through all of the The cold water:

dryer cylinders at a pressure above atmospheric pressure so that at notime .is there' a deficiency insteam to the wet end sec-.

tion 6" In some cases as in board mills the pressure or the steam in theWet end of section 6* to pp section may be as high as twenty-five poundsthereby providing a heatin source having high termperature where it ismost needed. The vacuum creating means 39 for exhausting the air andwater is separate from the wet end dryers, and in aiding the circulationof steam through them by condensing the steam reaching it, said meansindirectly aids in. removing the air and water from the dry end section6 and facilitating the steam circulation therein.

In cases where there is an insufficient supply or steam passing from thereturns 21 of the dry end section 6", through separator 26 to the wetend section 6, it is necessary to supply steam direct from the supplyheader header 32 of section 6, and this is accomplished automatically bythe following means. The headers 23 and 32 are connected by an arch pipe34 containing at its upper end a pressure, reducing valve 35 (moreclearly shown in Fig. 2) which may be set to maintain the steam pressurein the uvet end header 32 at a predetermined amount governed by the,pressure in the wet end section, and this may be setto respond tofluctuations in the supply header 32 or return header 33-, as de-.

sired. The pressure reducing valve is operated to open by the action ofa counterwcight 35 and to close under the pressure supplied fromthe. wetend section acting upon the diaphragm 35*, the said pressure supplied bya valve controlled pipe 36 from the supply header 32, or by a valvecontrolled pipe 37 from the return header 3 By this arrangement, whenthe weight 35 is once set for control by the variations in steampressure in' the supply header if, for any reason. there wasinsufficient steam to meet sudden increase of moisture in the paper, theengineer will close pipe 36 and open pipe 37, said action instantlycausing an increased automatic. steam supply through thepressurereducing valve 85 to .the wet end section 6 of the dryers. If the steamsupply should be in excess of the requirements (shown by the gauge G onreturn header 33) the pipe 717 is closed and pipe 36 is opened. In thismanner the apparatus has a' capacity under the control of the engineerfor quick change of steam supply when necessary and at other times theregulation is automatic. In case of special emergency, the engineer mayclose hoth pipes 36 and 37 allowing the valve 35 to open full 'or toclose one pipe and throttle the other to provide for further regulationof valve where a somewhat greater opening than normal is required. Theobject in all cases should be to provide as free circulation of steam aspossible with a sufficient final pressure above atmospheric pressure inthe wet end return-as will blow v the driers clear of water and air, thesteam passing to the duplex condensation pump 39 Where it is condensed,the heat units thus ab sorbed into the spray water being fully returnedto the boilerand thus doubly utilized.

Steam gages G are shown at various other of the total number of dryingcylinders in the dry .end section as compared with twenty-five per centin the wet end section, but this is by way of example and not as arestriction, the smallness ofthe drawing; precluding the actual showingof'the preferred full number of cylinders. Where the paper mill isintended for making paper board wherein the material to be dried isgreatly increased in bulk, it is desirable toincrease the number of dryend sections, to not only provide more drying surface but also tosupplymoresteam to the wet end section. I have shown in Fig.1 a

satisfactory construction for providing increased heating surface anddry end sections, the same comprising cylinder sections 6 and 6.Cylinders of section 6 are. sup-' plied with steam froma supplyheader 4:receiving exhaust steam by pipe 22 under control of valve 20, or livesteam from steam main 2 under control of valve 5. The water ofcondensation and nuiondensed steam from the cylinders of section 6 (ll$W:::

charge into the return header 7ipassiug therefrom by pipe 16 in which isarranged a steam separator 17 from which .the water passes by pipe 18 tothe return pipe 27. communicating with pipe 25 and ultimately deliveringinto the, condensation pump 29.- The steam from the separator 17 passesby a continuation of pipe 16 into a supply.

header 10, which supplies steam tothe cylinders '.of section 6*,the'water of condensation and steam therefrom passing to return header11 and thence by pipe 12 to the suction port of a vacuum condensationpump 13, supplied with spray water by pipe. 13 andcapable of condensinga portion of the steam and by removing back pressure.

permitting free circulation. The discharge from this pump .13 isdelivered by pipe 14.- into the main 1:) leading to the duplex boilerfeeder 43 before referred to. The steam pressure in sections 6 and 6 iffrom. er;- haust, may be 15 pounds in supply header it, 10 pounds inreturn header 7 and supply header l0, and 7 pounds in return header 11.If'higher pressure from live steam is required "(Where the paper boardis operate" to "automatically supply a suflicient quantity of steamtovsection 6 to meet drylng require'ments. It will be observed thatsections 6 and 6 are constructed androperate ery,.similarly to sections6 and 6, except that in thelatter case condensation pump -.ing cylindersare required to provide-a 29' is required to take'care of the water ofcondensation from section 6 and in part from sections 6 and 6 ,;whereasin the case of sections 6 and B the vacuum condensation pump 13 isrelied upon toremove the known types which'have' beenheretofore mamwater and aira-nd condense a part of the steam to improve steamcirculation in these sections, and a higher steam pressure may besupplied if so desired.

In referring to the various pumping dethe boiler feeder develope by meand are extensively in general use in other systems and 'itwill there-'fore be on-ly necessary to briefly define the characteristics .of theseparts of the general' vapparatus of my present invention.- The boilerfeeder 43 isnof'the type in which there is a tilting tank having twocompartments,

one filling with the feed vWater against atmospheric pressure, while theother is discharging by gravity into the boiler, accomdischarge beinggoverned the tank under-the filling and discharging lished sure to thecompartment, the control 0 the operations.

The duplex condensing pump 39 essentially comprises a tilting tankhavingtwo compartments alternately receiving water' of condensation andalternately dis charging to the boiler 'feederiunder the boiler steampressure, the steam thus supplied and utilized, together with that fromthe wet end cylinders being then condensed by Water sprays to provide apartial-vacuum in the compartments alternately and thus maintain avacuum and resulting suction upon the water and air in the return pipesof the dryingsection. ,The tilting tank condensation pumps 13 and 29 areordinarily.

single acting devices discharging intermittently and in the case of pump13, it is made to produce a partial vacuum by the employby admittingsteam at boiler resthe tilting of b ment of the spray waiter supplyvacuum produced operating to improve airculatidxfof steam through. thesections fia'nd 6 and in a' measure simulating the action of pump 39,though in a lesser degree in view of the fact that it is not at the wetveridjof thesystem; lVhileI prefer the tilting trap pumps as gameans forhandling the Water of condensation and condenslngthe steam to msureonculation of steam in the, wet end cylinders above atmosphericpressure, an ordinary vacuum pump with condensing Water spray maybe usedinstead; and similarly, aside from handling the water and air and forreturn of the Water to the boiler, any means suitable for condensing.the steampassing" from the we end return header 33 may be employed as,for instance, a; feed water heater. a

It will be-understood that none ofthe dryvacuum in maintained condition,and it is upon the duplex vacuum condensation pump ata pressure abovethat of the atmosphere.

.1 By my improved construction and mode f of operation, I obtain economyin the use of steam, insure';perfect circulation of the steamiaboveatmospheric pressure and effecthe drying thereby,

pressures to be supplied to the steam.

It will'now be apparent that I have de viseda novel and usefulconstruction which embodies the features of advantage enumerated asdesirable, ,and while I have in the present instance shown and describedthe preferred embodiment thereof which has een found in practice'to givesatisfactory and have" capacity for Q "regulation of the volume of steamat definite and reliable results,it is to be understood thathI dfo notrestrict myself tothe details, I as the same are susceptible ofmodification ,without departing fromthe spirit or 'scopeof theinvention.

Having thus described my invention, what in various particulars I claimas new and desireto secureby Let ters-PatentfisP I l A dryingapparatusfor paper making machineshaving drying cylinders arranged 'in' aplurality of sets constituting sections operating under differentpredetermined pressures, each-section provided with supply and returnheaders in which the supply header of} one section is connected with asource of steam and the return header of said section is connected todeliver its steam into the supply header of the next section of lowerpressure, combined with a receiving device for removing the air andWater of condensation from said section of lower pressure, a by-pass forsupplying steam from the supply header of the first mentioned section tothe supply header to the section of lower pressure, and automatic meansin the lay-pass for controlling the passage of steam therein whereby apredetermined differential pressure between the pressures in the twosupply headers may be maintained.

2. The invention according to claim 1, further characterized by havingthe two sections constitute a dry end section and a wet end section, andhaving the receiving device connected to the wet end section and steamis utilized therein with cold water spray-for producing the condensationof the steam and a local vacuum, whereby the water of con densation andsteam are delivered from the wet end section and steam at or aboveatmospheric pressure caused to circulate .through the same, and saidlive steam utilized for discharging the water or condensation from thereceiving device to the place of delivery. j

3. The invention according to claim 1, fur ther "having means forrece'ving and discharging the water of condensation from the 7 dry endreturn header, said means consisting of a tilting condens tion pinupwhose operation removes the water oi? condensation and delivers it tothe place of discharge and also supplies said water of condensation withthe heat of additional steam condensed by contact therewith.

4. The invention according to c having further, the two sections con wetand dry end sections means for receiving and removing waterotcondensation from the return header of the dry end section, a b vpassfor steam from the supply header of the dry end section to the supplyheader of the wet end sectionpand means in said by-pass for controllingthe pass... oi steam.

The invention according to claim 1, wherein the means in the b v-pascomprises an automatic pressure reducii valve for im 1, irutingmaintaining a general predetermined steam pressure in the section oflove pro. ,ure.

6. The invention according to claim 5, which the reducing valve. isprovided with means for enabling it to 01 rate to maintain asubstantially constant steam l l'USHHiG in the supply header of thelower pressure section.

7. The invention according to claim 3, in which the reducing valve isprovided w th means for enabling it to operate to main a substantiallyconstant steam pressure the return header of the wet end section.

8. The invention according to claim 0, wherein the reducing valve iscombined with hand ad uStable means 'for causing it to respond to thepressure of either the supply or return headers of the section of lowerpres sure toinsure sufficient steam supply to compensate for variationsin the. drying duty required of the section.

9. The invention according to claim 8, in A which the hand adjustablemeans for the.

pressure reducing valve comprise pipes leadmg fromjthe pressure reducingvalve and respectively communicate with the supply and return headers ofthe section of lower further combined with a steam boiler for" supplyingsteam to the'dry end section and also to the receiving devices of thewet end section and receiving-means of the dry end section for handlingthe condensation water from the return headers of the wet and dry endsections, respectively, and a boiler feeding device 'for and receivingthe heated water discharged from the receiving devices and means anddelivering it into the boiler, whereby the heat units of the steamutilized in handling the water of condensation are automaticallyreturned to the boiler.

11. The invention according to claim 1, further characterized by havingthe section of higher pressure supplemented by two additional sectionsof drying cylinders the said sections coupled in series so that thesteam from the returns of the last section is supplied to thenextsection, means to supply steam at desired pressure to the last andmost distant of said sections from the wet end section, and acondensation pumping means producing a partial vaeuumtherein' i'orremoving the water of condcnsatioirand insuring positive circulation ofsteam above atmospheric pressure in said additional sec- .ifhe inventionaccording to claim'll, having a bypass from the supply side of the lastsection to the supply side f the other at the additional dry endsecpressures in the next to last dry end section.

14. The herein described method of dry ing pape rinch con in supplyingsteam "from a source. to the dry end ,etion cylinders and delivering theuncondensed steam therci'rknn to the wet end section cylinders whilemaintaining the said steam pressures above atmospheric pressure,removing the water of condensation from said dry and wet end sectionsand delivering it to the source of steam, andgproduc'inga partial vacuumat a'place beyond-the wet end sectlon and between lt and the sourceof'steam for causing the water of condensatlon from the wet end sectiontobe freely drivenfro'm ingin passing the wet paper successively over aplurality of drying cylinders arranged in sets comprising dry' end andwet end sections, supplying steam to the dry end cylinders to heat them,passing the uncondensed steam from the dry end cylinders into the wetend cylinders for heating them, removing the water of condensation fromthe cylinders, supplying steam from the source directly to the cylindersof the wet end section without passing through the cylinders of the dryend section, and regulating the supply of steam thus supplied from thesource'directly to the wet end section under control of the steampressure varia tions in the wet end section to maintainasubstantiallyconstant predetermined difi'erential pressure between the'wet end and dry end sections.

16. The invention according to claim 15,- further characterized bycausing the regu-,

lation of the direct supply of steam to the wet end section to begoverned by the pressure in thesup'ply header or return-header thereof,at the will of the engineer.

17. The method of drying paper,"consist- 'ing in passing the wet paperweb successively over a pluralityof drying cylindersarranged in setscomprising dry end and wet end sections, supplying steam to the dry 'endcylinders to heat them, passing the uncondensed steam from the dry endcylinders into the wet end cylinders for beating them, passing water ofcondensation and un'condensed steam from the wetpressure'but abov e'condensation from. said v minimum resistance.

paper, consistend cylinders at a pressure above atmospheric pressure,condensing the steam after passing from and out of the influence of thewetend cylinders to remove back pressure and to permit the steam toflowthrough all of the cylinders at a pressure above atmosphericpressure and to blow the water of I cylinders with a 18. Thermethod ofdrying paper, consisting in passing the wet paper web successively-overa plurality of heated drying cylinders arranged in sets including dryend and wet end sections, supplying steam to the dry end section and thesteam received from the cylin'dersbf that section into the cylinders ofthe next section of lower pressure, removing the water of condensationand air from the last mentioned section to permit the steam to passfreely into the cylinders thereof, and maintaining a predeters mineddifferential in pressure between the steam supply pressures of theadjacent sections by causing steam to be directly bypassed from thesupply main of any one.

section to the supply main of the next section of lower pressure, 'saidby-passing'of the steam for regulation and maintenance of thepredetermined differential being in the direction from the dryendsection to the wet end section.

19. The method according to claim 18, wherein 'further, the by-passi'ng'of the steam is controlled by adi'op in the pressure -in the steamsupply .of' any section to such an extent as to make the differential inpressures between the pressure of the steam supply in which the dropoccurred and thev steam supply pressure to thesection from which thesteam was derived greater than I the predetermined differential.

In testimony of-whicli invention, I hereunto set. my hand.

FREnERicK c. FARNSWORTH.

